1. Field of the Invention
The present invention relates to an oscillator employing a stripline, and a method of manufacturing the same.
2. Description of the Background Art
FIG. 8 shows an exemplary conventional oscillator 1 employing a triplate type stripline 3. This oscillator 1 comprises a dielectric substrate 2 which is provided with the stripline 3 embedded therein and an oscillation circuit 4 which is mounted on the substrate 2 for inducing natural oscillation of the stripline 3. As shown in FIG. 9, two earth (ground) patterns 5 are formed in the interior and on the bottom surface of the substrate 2 respectively to hold the stripline 3, while earth electrodes 6 are formed on four side surfaces of the substrate 2 by printing or the like, and are electrically connected with the earth patterns 5. Thus, the earth patterns 5 and the earth electrodes 6 completely electromagnetically shield the periphery of the stripline 3, thereby reducing radiation loss of the stripline 3. An end (not shown) of the stripline 3 is connected to the earth patterns 5, while the other end (not shown) thereof is extended to the exterior of the substrate 2.
However, it is extremely difficult to form the earth electrodes 6 on the four side surfaces of the substrate 2, and hence the manufacturing cost is increased. When the substrate 2 is prepared from glass epoxy resin or the like, a large-area mother substrate 7 is generally cut into a plurality of substrates 2, as shown in FIG. 10. In this case, it is necessary to form the aforementioned earth electrodes 6 on respective of the plurality of substrates cut end surfaces. Thus, the manufacturing cost is so increased that it is difficult to carry out such a method in practice.